Navigating the Unnatural Reaction Space: Directed Evolution of Heme Proteins for Selective Carbene and Nitrene Transfer.
Navigating the Unnatural Reaction Space: Directed Evolution of Heme Proteins for Selective Carbene and Nitrene Transfer.
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DOI：
10.1021/acs.accounts.0c00591
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发表时间：
2021-03-02
影响因子：
18.3
通讯作者：
Arnold FH
中科院分区：
文献类型：
--
作者：
Yang Y;Arnold FH
尽管自然发生的生物催化过程的多样性令人惊讶，但酶并不能催化合成化学家喜欢的许多转化。要么大自然不关心特定的产品，要么她关心，她采取了不同的合成策略。在许多情况下，合成化学家使用的适当试剂对生物系统来说并不容易获得。在这里，我们讨论我们努力扩大酶的催化反应范围，以涵盖以前仅在小分子催化中已知的强大反应：反应性卡宾和硝基中间体的形成和转移，从而产生广泛的产品，包括具有生物学上未知的键的产品。鉴于参与细胞色素P450催化氧化的铁卡宾(Fe=C(R1)(R2))和氮铁(Fe=NR)与铁氧(Fe=O)中间体的结构相似性，我们使用了生物系统从未遇到过的合成卡宾和硝化前体，并改变了P450的用途来催化一些在自然界中未知的反应。由此产生的蛋白质催化剂是完全遗传编码的，并在完整的微生物细胞或无细胞裂解产物中发挥作用，在这些细胞或裂解产物中，它们的性能可以通过定向进化来改进和优化。通过利用P450酶的催化混杂，我们进化出一系列卡宾和硝基转移酶，对这些新的反应表现出良好的活性。自2012年我们首次报告以来，还发现了包括肌红蛋白、原球蛋白和细胞色素c在内的许多其他血红素蛋白，并对其进行了改造，以促进非自然的卡宾和氮的转移。由于活性中心环境的改变，这些血红素蛋白通常表现出对P450的互补活性和选择性。使用野生型和工程化的血红素蛋白，我们和其他人描述了一系列选择性的卡宾转移反应，包括环丙基化、环丙烯基化、Si-H插入、B-H插入和C-H插入。类似地，各种不对称的硝基转移过程，包括氮杂环化、硫化物亚胺化、C-H酰胺化，以及最近的C-H胺化，都已被证明。这些生物催化卡宾和硝烯转移反应的范围通常是对基于小分子过渡金属催化剂的最先进工艺的补充，使工程生物催化剂成为合成化学家工具箱中有价值的补充。此外，由于酶催化剂施加的精细区域和立体控制，这个生物催化平台提供了一个令人兴奋的机会来解决现代合成化学和选择性催化中的挑战性问题，包括合成化学家几十年来一直未能解决的问题。
Despite the astonishing diversity of naturally occurring biocatalytic processes, enzymes do not catalyze many of the transformations favored by synthetic chemists. Either nature does not care about the specific products, or if she does, she has adopted a different synthetic strategy. In many cases, the appropriate reagents used by synthetic chemists are not readily accessible to biological systems. Here, we discuss our efforts to expand the catalytic repertoire of enzymes to encompass powerful reactions previously known only in small-molecule catalysis: formation and transfer of reactive carbene and nitrene intermediates leading to a broad range of products, including products with bonds not known in biology. In light of the structural similarity of iron carbene (Fe=C(R1)(R2)) and iron nitrene (Fe=NR) to the iron oxo (Fe=O) intermediate involved in cytochrome P450-catalyzed oxidation, we have used synthetic carbene and nitrene precursors that biological systems have not encountered and repurposed P450s to catalyze reactions that are not known in the natural world. The resulting protein catalysts are fully genetically encoded and function in intact microbial cells or cell-free lysates, where their performance can be improved and optimized by directed evolution. By leveraging the catalytic promiscuity of P450 enzymes, we evolved a range of carbene and nitrene transferases exhibiting excellent activity toward these new-to-nature reactions. Since our initial report in 2012, a number of other heme proteins including myoglobins, protoglobins, and cytochromes c have also been found and engineered to promote unnatural carbene and nitrene transfer. Due to the altered active-site environments, these heme proteins often displayed complementary activities and selectivities to P450s. Using wild-type and engineered heme proteins, we and others have described a range of selective carbene transfer reactions, including cyclopropanation, cyclopropenation, Si–H insertion, B–H insertion, and C–H insertion. Similarly, a variety of asymmetric nitrene transfer processes including aziridination, sulfide imidation, C–H amidation, and, most recently, C–H amination have been demonstrated. The scopes of these biocatalytic carbene and nitrene transfer reactions are often complementary to the state-of-the-art processes based on small-molecule transition-metal catalysts, making engineered biocatalysts a valuable addition to the synthetic chemist’s toolbox. Moreover, enabled by the exquisite regio- and stereocontrol imposed by the enzyme catalyst, this biocatalytic platform provides an exciting opportunity to address challenging problems in modern synthetic chemistry and selective catalysis, including ones that have eluded synthetic chemists for decades.
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影响因子：
15
作者：
DOYLE, MP;PROTOPOPOVA, M;SHAPIRO, EA
通讯作者：
SHAPIRO, EA
DOI：
10.1038/s41570-019-0099-x
发表时间：
2019-06
期刊：
Nature reviews. Chemistry
影响因子：
--
作者：
Davies HML;Liao K
通讯作者：
Liao K
影响因子：
56.9
作者：
Coelho, Pedro S.;Brustad, Eric M.;Arnold, Frances H.
通讯作者：
Arnold, Frances H.
影响因子：
16.6
作者：
Cho, Inha;Prier, Christopher K.;Arnold, Frances H.
通讯作者：
Arnold, Frances H.
影响因子：
3.9
作者：
Clark, Jonathan P.;Miles, Caroline S.;Chapman, Stephen K.
通讯作者：
Chapman, Stephen K.